Communication device, communication device control method, and display system

ABSTRACT

A communication device is provided, which includes: a receiver that receives, in a case where the communication device is already connected to a first information processing device by a first connection method, a connection request from a second information processing device; and a controller that performs control such that, (1) in a case where a connection method designated in the connection request is a second connection method different from the first connection method, connection based on the connection request is not performed and that, (2) in a case where the connection method designated in the connection request is the first connection method, connection based on the connection request is performed, wherein the receiver receives image data from an information processing device connected to the communication device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 15/072,768,filed Mar. 17, 2016 the entire disclosure of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a communication device, a communicationdevice control method, and a display system.

Description of the Related Art

In general, a personal computer (PC) and a projector transmit andreceive image signals based on analog connection which uses an analogRGB cable. However, analog connection has a problem that it takes timeand labor and it is difficult to establish the connection from a remotesite and with a plurality of PCs. Due to these reasons, a network-basedscreen transfer system that connects a PC and a projector via a networkis gathering attraction.

In this network-based screen transfer system, a function of projecting avideo in one PC to a plurality of projectors simultaneously and afunction of projecting videos in a plurality of PCs to one projector ina large screen layout are realized. Moreover, Japanese PatentApplication Publication No. 2014-127915 discloses a method of managinginformation on a network group (hereinafter referred to as a session)made up of PCs and projectors and performing adding and removal of aprojector that forms the session.

However, in such a network-based screen transfer system, an access pointfunction is provided to a projector-side wireless LAN network IF itselfso that the projector-side wireless LAN network IF establishes a networkconnection directly with a PC-side wireless LAN network IF (hereinafterthis connection will be referred to as wireless direct connection).According to this method, a local network environment can be created bya PC and a projector only, and network-based screen transfer can berealized without other network devices such as a router, a hub, and anaccess point.

Since the projector does not perform routing between the cable LANnetwork IF and the wireless LAN network IF, a local network formed bywireless direct connection can be separated from a network on the cableLAN network IF side. For example, even when an intra-network isconstructed on the cable LAN network IF side, wireless direct connectioncan be configured such that users such as guests who do not have anaccess right to the intra-network can use the wireless directconnection.

SUMMARY OF THE INVENTION

However, the following problems occur when a cable LAN network IF and awireless LAN network IF are mounted on a projector. Referring to FIG. 1,first a PC 100 a establishes connection via a cable LAN network IF of aprojector 200 a to form a session. Subsequently, a PC 100 b establishesconnection between its own wireless LAN network IF and a wireless LANnetwork IF of a projector 200 b and participates in the session. Whenthe PC 100 a adds the projector 200 b to the session in this state, thePC 100 b cannot establish connection with the projector 200 b. Thesession information (belonging devices are the PC 100 a, the PC 100 b,the projector 200 a, and the projector 200 b) possessed by the PC 100 ais different from the session information (belonging devices are the PC100 a, the PC 100 b, and the projector 200 a) possessed by the PC 100 b.In such a state, when the PC 100 a performs control to project thescreen of the PC 100 b to the projector 200 b, for example, the PC 100 bcannot execute the projection since the PC 100 b cannot communicate withthe projector 200 b.

Thus, an object of the present invention is to suppress the occurrenceof a state in which a communication device and an information processingdevice cannot communicate with each other in a display system in which aplurality of communication devices and a plurality of informationprocessing devices are connected by a network.

According to a first aspect of the present invention, there is provideda communication device which is connected to a network and cancommunicate with an information processing device, the communicationdevice including: a receiver that, in a case where the communicationdevice is already connected to a first information processing device bya first connection method, receives a connection request from a secondinformation processing device; and a controller that performs controlsuch that, (1) in a case where a connection method designated in theconnection request is a second connection method different from thefirst connection method, connection based on the connection request fromthe second information processing device is not performed and that, (2)in a case where the connection method designated in the connectionrequest is the first connection method, connection based on theconnection request from the second information processing device isperformed, wherein the receiver receives image data from an informationprocessing device connected to the communication device.

According to a second aspect of the present invention, there is provideda method of controlling a communication device which is connected to anetwork and can communicate with an information processing device, themethod including: receiving, in a case where the communication device isalready connected to a first information processing device by a firstconnection method, a connection request from a second informationprocessing device; performing control such that, (1) in a case where aconnection method designated in the connection request is a secondconnection method different from the first connection method, connectionbased on the connection request from the second information processingdevice is not performed and that, (2) in a case where the connectionmethod designated in the connection request is the first connectionmethod, connection based on the connection request from the secondinformation processing device is performed; and receiving image datafrom an information processing device connected to the communicationdevice.

According to a third aspect of the present invention, there is provideda display system in which an information processing device and acommunication device are connected by a network, the communicationdevice including: a receiver that, in a case where the communicationdevice is already connected to a first information processing device bya first connection method, receives a connection request from a secondinformation processing device; and a controller that performs controlsuch that, (1) in a case where a connection method designated in theconnection request is a second connection method different from thefirst connection method, connection based on the connection request fromthe second information processing device is not performed and that, (2)in a case where the connection method designated in the connectionrequest is the first connection method, connection based on theconnection request from the second information processing device isperformed, wherein the receiver receives image data from an informationprocessing device connected to the communication device, and eachinformation processing device includes a transmitter that transmits aconnection request to the communication device and transmits image datato the connected communication device.

According to a fourth aspect of the present invention, there is provideda non-transitory computer-readable storage medium storing acomputer-executable program for causing a computer to function asfollowing units of a communication device, which is connected to anetwork and can communicate with an information processing device,including: a receiver that, in a case where the communication device isalready connected to a first information processing device by a firstconnection method, receives a connection request from a secondinformation processing device; and a controller that performs controlsuch that, (1) in a case where a connection method designated in theconnection request is a second connection method different from thefirst connection method, connection based on the connection request fromthe second information processing device is not performed and that, (2)in a case where the connection method designated in the connectionrequest is the first connection method, connection based on theconnection request from the second information processing device isperformed, wherein the receiver receives image data from an informationprocessing device connected to the communication device.

According to the present invention, it is possible to suppress theoccurrence of a state in which a communication device and an informationprocessing device cannot communicate with each other in a display systemin which a plurality of communication devices and a plurality ofinformation processing devices are connected by a network.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram of a network-based screen transfersystem;

FIG. 2 is a hardware configuration diagram of a PC and a projector;

FIGS. 3A and 3B are communication flowcharts of a PC and a projector;

FIGS. 4A to 4D illustrate a GUI of a PC;

FIGS. 5A to 5E are diagrams illustrating an OSD on a projectorprojection screen; and

FIGS. 6A to 6C are flowcharts of a connection reception process of aprojector.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described indetail with reference to the drawings, but this invention is not limitedto the following embodiment. Moreover, an embodiment of the presentinvention illustrates a preferred mode of the invention and does notlimit the scope of the invention.

Embodiment 1

Hereinafter, a main configuration of a PC 100 and a projector 200 thatforms a display system of Embodiment 1 will be described with referenceto FIG. 2. After the configuration is described, a basic operation willbe described. The display system of Embodiment 1 is made up of aplurality of information processing devices (the PCs 100) and one or aplurality of communication devices (the projectors 200) capable ofestablishing communication channels according to a plurality ofconnection methods by being connected to each other by a network. InFIG. 2, only one PC 100 and only one projector 200 are illustrated toprevent the drawing from being complicated. In this network, a displaydevice and an information processing device can establish communicationchannels according to a plurality of connection methods. In Embodiment1, although a cable LAN interface and a wireless LAN interface areillustrated as examples of the plurality of connection methods, theconnection method is not limited to this. For example, wirelesscommunication standards such as infrared or Bluetooth (registeredtrademark) can be used as the connection method, and wired communicationstandards such as USB or HDMI (registered trademark) can be used as theconnection method.

First, a main configuration of the PC 100 will be described.

A central processing unit (CPU) 101 controls the entire PC 100.

A random access memory (RAM) 102 is a main memory that stores data. TheRAM 102 is mainly used as various data storage areas such as an area forstoring or loading a program executed by the CPU 101 or a work area of aprogram in execution.

A video RAM (VRAM) 103 is used as an area for storing image data to bedisplayed on a display unit 106 (described later). If the processingspeed of the RAM 102 is sufficiently high, the VRAM 103 may be the sameas the RAM 102.

A read-only memory (ROM) 104 stores a boot program that the CPU 101executes during initialization. The boot program performs a process ofloading an operating system (OS) recorded in a hard disk drive (HDD) 105(described later) onto the RAM 102 and activating the OS.

The HDD 105 is used for storing data and programs such as an applicationprogram or an OS.

The display unit 106 displays an image instructed by a display controlunit 107 (described later). The display unit 106 is a liquid crystalpanel or an organic electro-luminescence (EL) panel, for example. Thedisplay unit 106 is not limited to these examples but may be acathode-ray tube (CRT), a micro electro mechanical system (MEMS) shutterdisplay, or the like.

The display control unit 107 performs a process of reading the imagedata stored in the VRAM 103 and displaying the image data on the displayunit 106.

An operating unit 108 receives an input operation from a user. Theoperating unit 108 includes a keyboard, a mouse, a touch panel, and thelike and the input operations of these components are transmitted to theCPU 101.

A cable LAN network interface (IF) 109 performs communication with anexternal device, specifically the projector 200.

A wireless LAN network IF 110 performs communication with an externaldevice, specifically the projector 200.

An internal bus 111 connects the respective processing blocks describedabove.

A basic operation of the PC according to Example 1 includes thefollowing steps. That is, a screen transfer program running on the CPU101 of the PC controls the display control unit 107 to capture imagedata being displayed by the display unit 106. The screen transferprogram running on the CPU 101 encodes the captured image data into apredetermined format that the projector 200 can recognize. The screentransfer program running on the CPU 101 transmits the encoded image datato the projector 200 via the cable LAN network IF 109 or the wirelessLAN network IF 110. Here, the screen transfer program includes agraphical user interface (GUI). By using the GUI, the screen transferprogram can receive various operations of the user, such as a “projectorconnection method selection process,” a “screen transfer destinationprojector selection process,” or a “screen transfer start/stop process”via the operating unit 108.

Next, a main configuration of the projector 200 will be described.

A CPU 201 controls the entire projector 200.

A RAM 202 is a main memory that stores data. The RAM 202 is mainly usedas various data storage areas such as an area for storing or loading aprogram executed by the CPU 101 or a work area of a program inexecution.

In a ROM 203, data such as a program or a parameter necessary for theprojector 200 to operate is stored in advance and the CPU 201 operatesaccording to the content stored in the ROM 203.

A VRAM 204 is used as an area for storing image data to be projected bya projection unit 206 (described later).

A decoder 205 decodes the image data received from the PC 100 when theimage data is encoded according to an encoding method such as JPEG, forexample.

The projection unit 206 displays image data instructed by a projectioncontrol unit 207 (described later). Specifically, the projection unit206 includes a liquid crystal panel, a lens, and a light source.

The projection control unit 207 performs a process of reading the imagedata stored in the VRAM 204 and outputting the image data to theprojection unit 206.

An operating unit 208 receives an input operation from a user. Theoperating unit 208 includes a button provided on a casing, a remotecontrol signal receiver that receives the user's operation from a remotecontroller (not illustrated), and the like, and information on the inputoperations of these components is transmitted to the CPU 201.

A cable LAN network IF 209 performs communication with an externaldevice, specifically the PC 100.

A wireless LAN network IF 210 has an access point function and performsa process of issuing a beacon signal including its own service setidentifier (SSID) and allocating an IP address to a wireless LAN clientdevice. Moreover, the wireless LAN network IF 210 performs communicationwith an external device, specifically the PC 100.

An internal bus 211 connects the respective processing blocks describedabove.

A basic operation of the projector 200 according to Example 1 involvesreceiving image data from the PC 100 (an information processing device)of which the communication channel with the projector 200 (a displaydevice) has been established and displaying an image. Specifically, theCPU 201 receives the image data transmitted from the PC 100 via thecable LAN network IF 209 or the wireless LAN network IF 210 according tothe program stored in the ROM 203. The CPU 201 loads the received imagedata into a format that the projector 200 can display with the aid ofthe decoder 205 and stores the image data in the VRAM 204. The CPU 201controls the projection control unit 207 and projects and displays animage based on the image data with the aid of the projection unit 206.

Here, a characteristic operation of the screen transfer system ofEmbodiment 1 will be described.

As described above, according to the network-based screen transfersystem of the present invention, it is possible to maintain a state inwhich an information processing device and a display controller cancommunicate with each other by unifying a connection method within anetwork group that forms the screen transfer system.

First, with reference to the communication flowcharts of FIGS. 3A and3B, a sequence in which a PC and a projector establishes a communicationchannel in an initial state in which no communication channel isestablished between the PC and the projector will be described for twoconnection methods. In this example, the two connection methods are“infrastructure connection” which uses a cable LAN interface and“wireless direct connection” which uses a wireless LAN interface.

In Embodiment 1, it is assumed that the PC 100 includes the cable LANnetwork IF 109 and the wireless LAN network IF 110 as illustrated inFIG. 2. It is also assumed that as illustrated in FIG. 2 the projector200 includes the cable LAN network IF 209 and the wireless LAN networkIF 210. For further simplification, it is assumed that “192.168.254.1”is allocated to the cable LAN network IF 109 of the PC 100 as an IPaddress, and an IP address is not allocated to the wireless LAN networkIF 210. It is assumed that “192.168.254.254” is allocated to the cableLAN network IF 209 of the projector 200 as an IP address. Further, it isassumed that “192.168.253.254” is allocated to the wireless LAN networkIF 210 as an IP address.

It is assumed that the wireless LAN network IF 210 includes an accesspoint function as described above and “PJ_ABCDE” is allocated to thewireless LAN network IF 210 as a SSID of the access point. A wirelessLAN network IF having an access point function generally switchesbetween an “access point mode” in which the wireless LAN network IF actsas an access point and a “client mode” in which the wireless LAN networkIF acts as a wireless LAN client. However, in Embodiment 1, to simplifythe description, it is assumed that the wireless LAN network IF operatesin the “access point mode” only.

Moreover, it is assumed that the cable LAN network IF 109 of the PC 100and the cable LAN network IF 209 of the projector 200 are connected onthe same network segment and can communicate on a TCP/IP level.

In Embodiment 1, a connection method of establishing a communicationchannel for allowing the PC 100 to transfer a screen to the projector200 with the aid of the cable LAN network IF 109 of the PC 100 and thecable LAN network IF 209 of the projector 200 will be referred to as“infrastructure connection.” Moreover, a connection method ofestablishing a communication channel for allowing the PC 100 to transfera screen to the projector 200 with the aid of the wireless LAN networkIF 110 of the PC 100 and the wireless LAN network IF 210 of theprojector 200 will be referred to as “wireless direct connection.” It isassumed that the screen transfer program running on the PC 100 isexecuted on the CPU 101, presents a GUI to a user via the display unit106, and receives an operation from the user via the operating unit 108.

As a first example, a communication process flow in which the PC 100transfers a screen to the projector 200 according to “infrastructureconnection” will be described with reference to FIG. 3A.

Upon receiving an activation instruction from the user, the screentransfer program running on the PC 100 displays a GUI illustrated inFIG. 4A and waits for the input of an instruction as to whether acommunication channel with the projector is to be established accordingto “infrastructure connection” or “wireless direct connection.” In thisexample, it is assumed that the user presses a button 400 to input aninstruction to establish the communication channel with the projectoraccording to “infrastructure connection.”

The projector in an initial state before the communication channel isestablished presents an IP address allocated thereto by projecting anon-screen display (OSD) illustrated in FIG. 5A. In Embodiment 1,“192.168.254.254” is allocated to the cable LAN network IF and“192.168.253.254” is allocated to the wireless LAN network IF. Moreover,“PJ_ABCDE” is allocated as the SSID of the access point of the wirelessLAN network IF. Further, in an initial state in which no communicationchannel is established between an information processing device (the PC)and a display device (the projector), the information on a plurality ofconnection methods with which a communication channel can be establishedbetween the information processing device and the display device may bedisplayed in the OSD. In the example of FIG. 5A, information indicatingthat the projector can be connected according to both connection methodsof “infrastructure connection” and “wireless direct connection” is alsopresented.

Returning to FIG. 3A, in S301, the CPU 201 of the projector 200 controlsthe cable LAN network IF 209 to distribute projector informationincluding at least the IP address allocated to the cable LAN network IF209 to the network. In this example, the IP address is 192.168.254.254.The CPU 101 of the PC 100 receives the projector information via thecable LAN network IF 109 and displays a GUI illustrated in FIG. 4Baccording to this information.

The GUI illustrated in FIG. 4B includes an area 402 in which the IPaddresses are displayed in a list form based on the received projectorinformation. The user can input an instruction to designate a projectorto which a screen is to be transferred by clicking on a checkbox 403 andpressing an OK button 404.

In this example, to simplify the description, it is assumed that oneprojector 200 to which the IP address “192.168.254.254” is allocated isselected.

In S302, the PC 100 and the projector 200 performs a connection processfor establishing a screen transfer communication channel. Specifically,the CPU 101 of the PC 100 transmits a connection request to the cableLAN network IF 209 of the projector 200 by controlling the cable LANnetwork IF 109. The projector 200 having received the connection requestperforms a connection reception process illustrated in FIG. 6A with theaid of the CPU 201 and control the cable LAN network IF 209 to transmita response to the network IF which transmitted the connection request.

Here, the control of a connection request in an initial state in whichno communication channel is established between an informationprocessing device (the PC) and a display device (the projector)connected to a network will be described with reference to FIG. 6A. Whena display device has received a connection request to establish acommunication channel with the display device from an informationprocessing device in an initial state, the display device establishes acommunication channel between the display device and the informationprocessing device which transmitted the connection request according toa connection method designated in the connection request. That is, whena projector has received a connection request according to“infrastructure connection” from a PC in an initial state, the projectorestablished a communication channel according to infrastructureconnection. When the projector has received a connection requestaccording to “wireless direct connection,” the projector establishes acommunication channel according to wireless direct connection.Hereinafter, the process of receiving the connection request from the PCin the initial state of the projector will be described in detail.

First, in S600, if the cable LAN network IF 209 has received theconnection request, the CPU 201 of the projector 200 determines that theconnection request from the PC 100 is received according to“infrastructure connection” and proceeds to S601. If the wireless LANnetwork IF 210 has received the connection request, it is determinedthat the connection request from the PC 100 is received according to“wireless direct connection” and the flow proceeds to S604. In thisexample, it is assumed that the flow proceeds to S601 since“infrastructure connection” is received.

In S601, the CPU 201 of the projector 200 projects an OSD illustrated inFIG. 5B by controlling the projection control unit 207 and proceeds toS602. With the information displayed in the OSD of FIG. 5B, it ispossible to present information that the connection method acceptable tothe projector is “infrastructure connection” only. In this example, theOSD of FIG. 5B is displayed when a display device (the projector) hasreceived a connection request from an information processing device (thePC) according to infrastructure connection before the display device andthe information processing device establish connection according toinfrastructure connection. However, the OSD of FIG. 5B may be displayedas information on a connection method applicable to a device which isnot connected to a communication channel when the communication channelis already established between a display device and an informationprocessing device on a network according to infrastructure connection.

In S602, the CPU 201 of the projector 200 performs control to switch aconnection reception process to the process of FIG. 6B when a connectionrequest is received from a PC in the future. In S603, the CPU 201transmits a response to accept connection as to the connection requestreceived from the PC in S600 to a network IF (in this example, the cableLAN network IF 109 of the PC 100) that transmitted the connectionrequest and completes the process. With the above process, a logicalgroup (a session) for performing a screen transfer operation isestablished between the PC 100 and the projector 200.

The description will be continued by returning to FIGS. 3A and 3B. Aftera connection process is completed in S302, the CPU 101 of the PC 100displays a GUI illustrated in FIG. 4C.

The GUI illustrated in FIG. 4C includes a layout area 405 in which aprojection layout can be set, a tab 406 for changing a target projectorof which the projection layout is set, and an area 407 in whichinformation of the PC itself is displayed. The GUI of FIG. 4C furtherincludes a list 408 in which information of the other PCs belonging tothe session is displayed and a button 409 for adding or removing aprojector to or from the session. The GUI of FIG. 4C further includes abutton 410 for issuing an instruction to start a screen transferoperation to a projector being selected by the tab 406, a button 411 forissuing an instruction to stop the screen transfer operation, and abutton 412 for issuing an instruction to remove the PC from the session.Since the processes of the GUI are not the main idea of the presentinvention, the details thereof will not be provided (see Japanese PatentApplication Publication No. 2014-127915).

Returning to FIG. 3A, in S303, the PC 100 having receive the instructionto start a screen transfer operation from the user performs a process ofcapturing, encoding, and transmitting image data as described above. Theprojector 200 performs a process of receiving, decoding, and projectingthe image data as described above.

Hereinabove, a process flow in which the PC establishes a screentransfer communication channel to the projector in an initial stateaccording to “infrastructure connection” and performs a screen transferoperation has been described. A connection reception process subsequentto this corresponds to the flow described in FIG. 6B as described above.

In this example, the process when the projector 200 has received aconnection request for establishing a communication channel from anotherPC after a communication channel was established with the PC 100according to “infrastructure connection” will be described.

In S606, the CPU 201 of the projector 200 determines whether theconnection request is received according to “infrastructure connection”or “wireless direct connection” based on the network IF that hasreceived the connection request similarly to S600. The flow proceeds toS607 if the request was received according to “infrastructureconnection” and proceeds to S608 if the request was received accordingto “wireless direct connection.”

In S607, the CPU 201 of the projector 200 transmits a response to acceptconnection to the network IF of the PC that transmitted the connectionrequest and completes the process. Since the PC having received theresponse to accept the connection can participate in the session towhich the projector belongs, a GUI illustrated in FIG. 4C is displayed.That is, when the connection method of the communication channel is thesame as the connection method designated in the connection request(S606: Infrastructure connection), the CPU 201 accepts connection to acommunication channel of the information processing device thattransmitted the connection request (S608).

In S608, the CPU 201 of the projector 200 transmits a response to rejectconnection to the network IF of the PC that transmitted the connectionrequest and completes the process. That is, when the connection methodof the communication channel is different from the connection methoddesignated in the connection request (S606: Wireless direct connection),the CPU 201 rejects connection to a communication channel of theinformation processing device that transmitted the connection request(S607).

In this case, the information processing device may display a notice onthe GUI of FIG. 4B, indicating that the connection was rejected sincethe connection method of an existing communication channel that has beenestablished between a display device and an information processingdevice is different from the connection method designated in theconnection request for connection to the communication channel. That is,the PC having received the response to reject the connection has alreadyselected an IP address of a connection target projector on the GUI ofFIG. 4B. Thus, a notice that establishment of a communication channelhas failed since the projector has already established a communicationchannel according to “infrastructure connection” may be displayed on theGUI.

Hereinabove, a specific example of a process of receiving a connectionrequest for connection to a communication channel which is alreadyestablished between an information processing device (the PC 100) and adisplay device (the projector 200) on a network from another informationprocessing device (the PC) connected to the network. The CPU 201controls connection to a communication channel of an informationprocessing device that transmitted a connection request based on theconnection method of the communication channel and the connection methoddesignated in the connection request. In the above example, theconnection method of the communication channel is infrastructureconnection.

When all PCs having established a screen transfer communication channelwith a projector which has established a communication channel accordingto “infrastructure connection” cancel the communication channel, theprojector 200 returns to an initial state. In this case, the projector200 waits for any connection method, “infrastructure connection” or“wireless direct connection.”

As a second example, a communication process flow in which the PC 100transfers a screen to the projector 200 according to “wireless directconnection” will be described with reference to FIG. 3B.

Upon receiving an activation instruction from the user, the screentransfer program running on the PC 100 displays the GUI illustrated inFIG. 4A and waits for the input of an instruction as to whether acommunication channel with the projector is to be established accordingto “infrastructure connection” or “wireless direct connection.” In thisexample, it is assumed that the user presses a button 401 to input aninstruction to establish the communication channel with the projectoraccording to “wireless direct connection.”

As described in the communication process flow in which the PC 100transfers a screen to the projector 200 according to “infrastructureconnection,” a projector in an initial state before a communicationchannel is established projects the OSD illustrated in FIG. 5A.

In S311, the CPU 201 of the projector 200 controls the wireless LANnetwork IF 210 having an access point function to transmit a beaconsignal. The beacon signal includes identification information such as aSSID or an encryption scheme. In this way, the PC 100 within the reachof the beacon signal can understand that a local network for performingcommunication with the projector 200 is generated. The CPU 101 of the PC100 displays a GUI illustrated in FIG. 4D according to the informationin the received beacon signal.

The GUI of FIG. 4D includes an area 413 in which SSIDs are displayed ina list form based on the received beacon signal. In this GUI, the usercan input an instruction to designate a target projector to which ascreen is to be transferred by selecting a SSID of the target projector.The projector 200 displays the OSD illustrated in FIG. 5A and the SSIDof the projector is displayed in the OSD. Thus, the user may check theSSID on the projection screen of the target projector to which the userwants to transfer a screen and then select the SSID of the targetprojector in the GUI of FIG. 4D. In this example, to simplify thedescription, it is assumed that the projector 200 that possesses theSSID “PJ_ABCDE” is selected.

In S312, authentication is conducted between the PC 100 and theprojector 200. In this example, the projector 200 sends anauthentication response in response to an authentication request fromthe PC 100.

In S313, wireless connection is performed between the PC 100 and theprojector 200. In this example, the projector 200 sends an associationresponse in response to an association request from the PC 100, andframe exchange, parameter negotiation, AID (association ID) allocation,and the like are performed. In this way, the wireless connection betweenthe PC 100 and the projector 200 is completed.

In S314, the CPU 201 of the projector 200 calculates an IP address to beassigned to the PC 100 to allow the PC 100 to communicate with theprojector and notifies the PC 100 of the IP address by controlling thewireless LAN network IF 210. The CPU 101 of the PC 100 receives the IPaddress with the aid of the wireless LAN network IF 110 and allocatesthe IP address to the wireless LAN network IF 110. In this example, theIP address is “192.168.253.1.” After that, the PC 100 and the projector200 can communicate on a TCP/IP level.

In S315, a connection process for establishing a screen transfercommunication channel is performed similarly to S302. Specifically, theCPU 101 of the PC 100 control the wireless LAN network IF 110 totransmit a connection request to the wireless LAN network IF 210 of theprojector 200. The projector 200 performs the connection receptionprocess illustrated in FIG. 6A with the aid of the CPU 201 and controlthe wireless LAN network IF 210 to transmit a response to the network IFof the PC that transmitted the connection request.

Here, a connection reception process when a projector has received aconnection request from a PC according to “wireless direct connection”in an initial state (a state in which a screen transfer communicationchannel is not established with the PC) will be described in detail withreference to FIG. 6A.

First, since the wireless LAN network IF 210 has received the connectionrequest, the CPU 201 of the projector 200 determines in S600 that theconnection request is received according to “wireless direct connection”and proceeds to S604.

In S604, the CPU 201 of the projector 200 projects an OSD illustrated inFIG. 5C by controlling the projection control unit 207 and proceeds toS605. With the information displayed on the OSD of FIG. 5C, it ispossible to present information that the connection method acceptable tothe projector is “wireless direct connection” only. In this example, theOSD of FIG. 5C is displayed when a display device (the projector) hasreceived a connection request from an information processing device (thePC) according to infrastructure connection before the display device andthe information processing device establish connection according towireless direct connection. However, the OSD of FIG. 5C may be displayedas information on a connection method applicable to a device which isnot connected to a communication channel when the communication channelis already established between a display device and an informationprocessing device on a network according to wireless direct connection.

In S605, the CPU 201 of the projector 200 performs control to switch aconnection reception process to the process of FIG. 6C when a connectionrequest is received from a PC in the future. In S603, the CPU 201transmits a response to accept connection as to the connection requestreceived from the PC in S600 to a network IF (in this example, thewireless LAN network IF 110 of the PC 100) that transmitted theconnection request and completes the process. With the above process, alogical group (a session) for performing a screen transfer operation isestablished between the PC 100 and the projector 200.

The description will be continued by returning to FIGS. 3A and 3B. Aftera connection process is completed in S315, the CPU 101 of the PC 100displays the GUI illustrated in FIG. 4C.

The process of S316 is the same as that of S303 and the descriptionthereof will not be provided.

Hereinabove, a process flow in which the PC establishes a screentransfer communication channel to the projector in an initial stateaccording to “wireless direct connection” and performs a screen transferoperation has been described. A connection reception process subsequentto this corresponds to the flow described in FIG. 6C as described above.

In this example, the process when the projector 200 has received aconnection request for establishing a communication channel from anotherPC after a communication channel was established with the PC 100according to “wireless direct connection” will be described.

In S609, the CPU 201 of the projector 200 determines whether theconnection request is received according to “infrastructure connection”or “wireless direct connection” based on the network IF that hasreceived the connection request similarly to S600 and S606. The flowproceeds to S610 if the request was received according to“infrastructure connection” and proceeds to S611 if the request wasreceived according to “wireless direct connection.”

In S610, the CPU 201 of the projector 200 transmits a response to acceptconnection to the network IF of the PC that transmitted the connectionrequest and completes the process. Since the PC having received theresponse to accept the connection can participate in the session towhich the projector belongs, the GUI illustrated in FIG. 4C isdisplayed.

In S611, the CPU 201 of the projector 200 transmits a response to rejectconnection to the network IF of the PC that transmitted the connectionrequest and completes the process. The PC having received the responseto reject the connection has already selected a SSID of a connectiontarget projector on the GUI of FIG. 4D. Thus, a notice thatestablishment of a communication channel has failed since the projectorhas already established a communication channel according to “wirelessdirect connection” may be displayed on the GUI.

Hereinabove, a process when a connection request is received fromanother PC after a communication channel was established between anarbitrary PC and a projector according to “wireless direct connection”has been described.

When all PCs having established a screen transfer communication channelwith a projector which has established a communication channel accordingto “wireless direct connection” cancel the communication channel, theprojector 200 returns to an initial state. In this case, the projector200 waits for any connection method, “infrastructure connection” or“wireless direct connection.”

According to the configuration described above, it is possible tounifying a connection method within a network group that forms a screentransfer system. In this way, the occurrence of the state described inconnection with the object of the present invention is suppressed. Thatis, the occurrence of a state in which, when an instruction to projectthe screen of the PC 100 b using the projector 200 b is issued, theinstruction cannot be executed since the PC 100 b cannot communicatewith the projector 200 b is suppressed. This is because the PC 100 b isrejected when the connection request is issued to the projector 200 a.According to the configuration of Embodiment 1, even when a projector isadded to a session by a PC having participated in the session, all PCsbelonging to the session can communicate with the projector. In thisway, the occurrence of a state in which a display device and an imageoutput device cannot communicate with each other is suppressed.

In Embodiment 1, although both the cable LAN network IF and the wirelessLAN network IF are active in the initial state of the projector 200, thecable LAN network IF only may be active. In this case, the projector 200in the initial state can present information that the wireless LANnetwork IF thereof is inactive and “wireless direct connection” cannotbe accepted by projecting an OSD illustrated in FIG. 5D.

Moreover, the wireless LAN network IF only may be active. In this case,the projector 200 in the initial state can present information that thecable LAN network IF thereof is inactive and “infrastructure connection”cannot be accepted by projecting an OSD illustrated in FIG. 5E.

In the embodiment, a projector has been illustrated as an example of adisplay device which is connected to a network and can establish acommunication channel with an information processing device according toa plurality of connection methods and which receives image data from aninformation processing device with which a communication channel hasbeen established and displays an image. However, the display device isnot limited to the projector, but may be a liquid crystal display, anorganic EL display, a MEMS shutter display, or the like.

A device that controls a display process and a device that controls acommunication process may be included in the same casing as illustratedin FIG. 2 and may be separate devices. For example, a communicationdevice may be detachably attached to a display device such as aprojector.

The information processing device is not limited to the PC, but a mobilephone, a so-called tablet device, and the like may be used, for example.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2015-056737, filed on Mar. 19, 2015, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A display device which can be connected to anexternal device via a network, the display device comprising: acommunication interface that communicates with the external devices, anda display unit that displays an image based on image data received fromthe external devices by the communication interface, wherein the displayunit displays: (1) in a case where no connection has been establishedbetween the display device and another external device, a presentationimage to inform a user that the display device can be connected to theexternal device by either a first connection method or a secondconnection method which is different from the first connection method;(2) in a case where a connection has been established between thedisplay device and another external device by the first connectionmethod, a presentation image to inform the user that the display devicecan be connected to the external device by the first connection methodbut not by the second connection method; and (3) in a case where aconnection has been established between the display device and anotherexternal device by the second connection method, a presentation image toinform the user that the display device can be connected to the externaldevice by the second connection method but not by the first connectionmethod.
 2. The display device according to claim 1, wherein thecommunication interface includes a cable LAN interface and a wirelessLAN interface.
 3. The display device according to claim 2, wherein thefirst connection method establishes a communication channel via thecable LAN interface, and the second connection method establishes thecommunication channel via the wireless LAN interface.
 4. The displaydevice according to claim 1, wherein the presentation image is OSD (OnScreen Display) image.
 5. The display device according to claim 1,wherein the display unit is a projection unit that projects the imagebased on the image data.
 6. A method of controlling a display devicewhich can be connected to an external device via a network and displaysan image based on image data received from the external device, themethod comprising: displaying: (1) in a case where no connection hasbeen established between the display device and another external device,a presentation image to inform a user that the display device can beconnected to the external device by either a first connection method ora second connection method which is different from the first connectionmethod; (2) in a case where a connection has been established betweenthe display device and another external device by the first connectionmethod, a presentation image to inform the user that the display devicecan be connected to the external device by the first connection methodbut not by the second connection method; and (3) in a case where aconnection has been established between the display device and anotherexternal device by the second connection method, a presentation image toinform the user that the display device can be connected to the externaldevice by the second connection method but not by the first connectionmethod.
 7. A non-transitory computer-readable storage medium storing acomputer-executable program to execute a method of controlling a displaydevice which can be connected to an external device via a network anddisplays an image based on image data received from the external device,the method comprising: displaying: (1) in a case where no connection hasbeen established between the display device and another external device,a presentation image to inform a user that the display device can beconnected to the external device by either a first connection method ora second connection method which is different from the first connectionmethod; (2) in a case where a connection has been established betweenthe display device and another external devices by the first connectionmethod, a presentation image to inform the user that the display devicecan be connected to the external device by the first connection methodbut not by the second connection method; and (3) in a case where aconnection has been established between the display device and anotherexternal device by the second connection method, a presentation image toinform the user that the display device can be connected to the externaldevice by the second connection method but not by the first connectionmethod.